Marine‑traffic data shows that three Iranian oil tankers crossed a U.S. blockade line in the Gulf of Oman, carrying 3.8 million barrels of crude. The vessels—Diona, Hero II and Sonia I—began broadcasting their positions only once, the first time since March.
The ships left Chabahar port on Tuesday, sailing ahead of a U.S. naval line that stretches from Oman’s eastern tip to Iran’s coast. U.S. officials said the blockade would remain until a new agreement could be reached in Switzerland, slated for Friday.
Windward Maritime Intelligence’s senior analyst Michelle Bockman said the move indicates Iran’s confidence that the embargo has ended, as the ships already crossed the line and veered southeast.
All three vessels belong to the National Iranian Tanker Company, which, along with its ships, has been sanctioned by the U.S. Treasury. That last year the blockade trimmed Iran’s export to 260,000 barrels per day, a fraction of the 1.67 million average in 2025.
The tankers showed no destination after crossing, but Kpler data warns that the U.S. could enforce the blockade outside the Gulf, as it has done with Iranian ships in the Indian Ocean.
Other Iranian‑linked vessels have become active elsewhere: Stream halted its position before the blockade, and Dan and Sinopa were seen moving through the Strait of Malacca toward Iran.
The surge in activity marks a shift after Washington’s deal announcement, with United Against Nuclear Iran praising the move as a sign of Iranian urgency to resume shipping. The tankers’ movement, Bockman added, underlines how quickly Tehran is redeploying its fleet.
Additional reporting by Barbara Metzler
